5-Hydroxydiphenyl sulfoxide compositions

ABSTRACT

Polyolefins are stabilized against heat and light degradation by including in said polyolefins an unsymmetrical 5-hydroxydiphenyl sulfoxide.

BACKGROUND OF THE INVENTION

Polyolefins are subject in many applications to degradation caused bythe deleterious effects of heat and light. Many stabilizers have beenemployed to protect such polymers from degradation but they have notbeen completely satisfactory in providing protection from both heat andlight degradation, and often introduce color problems. Aromatic sulfurcompounds have been used as heat stabilizers for rubber and polyolefinsincluding bis(5-methyl-3-butyl-2-hydroxyphenyl) monosulfide. Symmetricalpolyhydroxy compounds such as 4,4'-thiobis(resorcinol) and the like havebeen used in bleaching and stabilizing wood rosin. However, suchmaterials have not been completely satisfactory in providing both heatand light resistance to polymers exposed to heat and light, particularlythe polyolefins.

SUMMARY OF THE INVENTION

5-Hydroxydiphenyl sulfoxides (sulfide S-oxide) of the general formula##STR1## wherein R₁ is hydrogen, R₂ is a lower alkyl as defined orhalogen as defined, wherein R₃ is hydrogen or a lower alkyl as definedsuch as methyl and t-butyl, R₅ is lower alkyl as defined, R₆ is hydrogenor lower alkyl as defined and R₇ is hydrogen or lower alkyl as defined,are useful in protecting polyolefins from the degradative effects ofheat and light. Lower alkyl means those radicals containing 1 to 12carbon atoms, preferably 1 to 8, and the alkoxy groups contain 1 to 6carbon atoms. T-Alkyl groups provide products with an excellent balanceof properties. The halogen is chlorine or bromine.

DETAILED DESCRIPTION

The 5-hydroxydiphenyl sulfoxides are prepared by reacting anarylsulfinyl chloride with a phenol.

The arylsulfinyl chlorides are easily prepared by reacting a phenylmercaptan of the formula ##STR2## or a diphenyl disulfide of the formula##STR3## with chlorine and acetic anhydride at -10° C. to form thearylsulfinyl chloride ##STR4## WHEREIN R₁, and R₂ are normally hydrogen,a halogen such as chlorine, a lower alkyl group containing 1 to 8 carbonatoms including methyl, t-butyl, and the like.

The arylsulfinyl chlorides are reacted with phenols of the generalformula ##STR5## in the presence of aluminum chloride and methylenechloride at 0° C. to provide unsymmetrical 5-hydroxydiphenyl sulfoxidesof the general formula ##STR6## wherein R₁ is hydrogen, R₂ is a loweralkyl as defined or halogen as defined, wherein R₃ is hydrogen or alower alkyl as defined such as methyl and t-butyl, R₅ is lower alkyl asdefined, R₆ is hydrogen or lower alkyl as defined as methyl and R₇ ishydrogen or lower alkyl as defined.

In the reaction of arylsulfinyl chloride with the phenol, about 1 mol ofthe arylsulfinyl chloride and about one mol of phenol are reacted withat least an equimolar amount of aluminum chloride in a polar solvent ata temperature preferably below about 25° C. If the temperature isconducted at too low a temperature, the reaction is too slow to bepractical, and more preferably is greater than about 0° C. While molarexcess or reactants may be used, there is no real advantage, and lessthan molar amounts of a reactant will result in lower yields. A usefulsolvent is dichloromethane and other solvents including chloroform,benzene, trichloroethane, ethylene dichloride, and the like may be usedas solvents. An advantage of this one step reaction is that total yieldsgreater than about 50% can be obtained.

The 5-hydroxydiphenyl sulfoxides in amounts as low as 0.01, morepreferably about 0.1 to as high as 5 to 10 weight parts per 100 weightparts of polymer provide increased resistance to heat and light induceddegradation in polyolefins.

Polyolefins having molecular weights of at least about 2000 which may bephotostabilized in accordance with this invention include homopolymersof α-olefins including those of ethylene, propylene, butene-1,isobutylene, pentene-1, hexene-1, 4-methyl-1-pentene, and the like;copolymers thereof such as ethylene, propylene, ethylene butene-1,4-methyl-1-pentene, hexene-1, and the like; ethylene α-olefin dienerubbers wherein the α-olefin is preferably propylene or butene-1 and thediene is 1,4-hexadiene, 2-methyl-1,4-hexadiene,dimethyl-1,4,9-decatriene, dicyclopentadiene, vinyl cyclohexane, vinylnorbornene, 2-ethylidene norbornene, norbornadiene, methyltetrahydroindene, and the like as is well known.

The 5-hydroxydiphenyl sulfoxides are readily incorporated into thepololefins by conventional methods including powder mixing, milling orbanbury mixing, extruding and the like, as such; in a solvent ormasterbatched. Conventional compounding ingredients will also be used inconjunction with the sulfoxide; including fillers, reinforcing agents,processing oils, plasticizers, lubricants, curing agents, antioxidants,antiozonants, color and heat stabilizers, other ultraviolet absorbers,and the like.

These sulfoxides have been found to be particularly useful when used inconjunction with other stabilizers, particularly aromatic hydroxystabilizers, and more particularly, unexpected synergistic activity isobtained with certain hydroxyphenyl alkeneyl isocyanurates of theformula ##STR7## wherein Y is a hydroxyphenylalkyleneyl radical havingthe formula ##STR8## wherein m is an integer from 1 to 4, r₁ is an alkylgroup positioned immediately adjacent to the hydroxyl group on the ringand contains from 1 to 18 carbon atoms and r₂, r₃ and r₄ are selectedfrom the group consisting of hydrogen or an alkyl group containing from1 to 18 carbon atoms; and Y₁ and Y₂ are selected from the groupconsisting of hydrogen or Y. The amounts of the combination used will befrom about 0.5 total to about 10 weight parts per 100 weight parts ofpolymer in a value of about 1:10 to 10:1 of each.

To demonstrate the practice of the invention, a series of5-hydroxydiphenyl sulfoxides were prepared and tested for stabilizingactivity in polypropylene.

The 5-hydroxydiphenyl sulfoxides used in the practice of this inventionare readily prepared by adding one equivalent of the arylsulfinylchloride dropwise to a well stirred suspension or solution of oneequivalent of a substituted phenol and one equivalent of anhydrousaluminum chloride in methylene chloride at 0° C. under a nitrogenatmosphere. This mixture is usually stirred for about 3 hours at thistemperature. Water is then slowly added until the solid product in thereaction product is dissolved. The layers are separated and the organicportion is dried over anhydrous magnesium sulfate, filtered andevaporated to a dark oil or solid. The oil or solid reaction product ispurified by washing with cold solvent or recrystallized from thesolvent. The structure of the 5-hydroxydiphenyl sulfoxides was verifiedby melting point, infrared or NMR spectroscopy and most by elementalanalysis for C, H, and S. The compounds were tested for stabilizingactivity by blending the amount shown in the tables as parts per hundredof polypropylene and the blend extruded, pressed into 10 mil thicksheets from which 1 × 2 samples were cut. The samples were then moldedon cardboard holders of a size to fit an IR spectrometer. The sampleswere placed in a Xenon weatherometer and at various time intervals thesamples were removed and IR spectra from 1910 to 1700 cm ⁻¹ arerecorded. A development of carbonyl groups at 1720 cm⁻¹ relative to areference peak at 1890 cm⁻¹ (the carbonyl index) against time ismonitored. The time for the carbonyl index to reach about 40 is thefailure time. The 5-hydroxydiphenyl sulfoxides were screened forphotostabilization activity in polypropylene by mixing intopolypropylene 0.1 to 0.5 weight part per 100 weight parts ofpolypropylene. Samples were tested for heat-antioxidant activity bymolded sample plaques separated by porcelain spacers on a glass rodwhich were placed in a draft oven at 140° C. The failure time is thatpoint in time when any portion of the plaque becomes brittle.

Following the general procedure set forth above, a series of5-hydroxydiphenyl sulfoxides were prepared using the arylsulfinylchloride and phenol set forth in the table and the yield, crystallizingsolvent and m.p. set forth. The concentration of sulfoxide in weightparts per 100 weight parts of polypropylene are also set forth with theresults of the oven and weatherometer aging.

    __________________________________________________________________________    Aryl                                                     Weather-             sulfinyl                    %   m.p.(° C)                                                                       Conc.                                                                             Oven-aging                                                                                ometer               chloride                                                                            Phenol Products       Yield                                                                             (solvent)                                                                              (phr)                                                                             125°                                                                       140°                                                                       150°                                                                       (hours)              __________________________________________________________________________    Control                                                                              --      --           --  --       0   11/2                                                                              1/3 1/3 200                  Benzene-                                                                            4-methoxy                                                                            2-methoxy-5-hydroxy-                                                                         44  142.5-144.5                                                                            0.5 6   11/3                                                                              1                        sulfinyl                                                                            phenol diphenyl sulfide   (ethyl                                        chloride     S-oxide            acetate)                                      Benzene-                                                                            4-ethoxy                                                                             2-ethoxy-5-hydroxy-                                                                          25  153-156  0.5 61/3                                                                              21/3                                                                              1   500                  sulfinyl                                                                            phenol diphenyl sulfide   (acetone)                                     chloride     S-oxide                                                          Benzene-                                                                            4-n-butoxy                                                                           2-n-butoxy-5-hydroxy-                                                                        65  134-136  0.1 41/3                                                                              1   1                        sulfinyl                                                                            phenol diphenyl sulfide   (methanol)                                    chloride     S-oxide                                                          __________________________________________________________________________

Other compounds prepared include 5-hydroxy-2-methoxy-4'-chlorodiphenylsulfide S-oxide prepared from 4-chlorobenzenesulfinyl chloride and4-methoxyphenol; 5-hydroxy-2-ethoxy-4'-chlorodiphenyl sulfide S-oxidefrom 4-chlorobenzenesulfinyl chloride and 4-ethoxyphenol.

I claim:
 1. A polyolefin containing a stabilizing amount of a5-hydroxydiphenyl sulfoxide of the formula ##STR9##wherein R₁ ishydrogen, R₂ is a lower alkyl or halogen as defined, wherein R₃ ishydrogen or a lower alkyl, R₅ is lower alkyl from 1 to 6 carbon atoms,R₆ is hydrogen or lower alkyl and R₇ is hydrogen or lower alkyl from 1to 6 carbon atoms.
 2. A polyolefin of claim 1 wherein the5-hydroxydiphenyl sulfoxide is present in amounts of about 0.1 to 10weight parts per 100 weight parts of polyolefin.
 3. A composition ofclaim 2 wherein said polyolefin is polypropylene.
 4. A composition ofclaim 3 wherein said sulfoxide is 2-ethoxy-5-hydroxydiphenyl sulfoxide.5. A composition of claim 3 wherein said sulfoxide is2-methoxy-5-hydroxydiphenyl sulfoxide.
 6. A composition of claim 3wherein said sulfoxide is 2-n-butoxy-5-hydroxydiphenyl sulfoxide.
 7. Acomposition of claim 3 wherein said sulfoxide is5-hydroxy-2-methoxy-4'-chlorodiphenyl sulfoxide.
 8. A composition ofclaim 3 wherein said sulfoxide is 5-hydroxy-2-ethoxy-4'-chlorodiphenylsulfoxide.